Detecting proximity using WiFi hotspots

ABSTRACT

A method of includes receiving hotspot identification data from the first device, where the identification data identifies a plurality of WiFi hotspots that are in proximity to the first device; determining that the second device is associated with the first device; sending the hotspot identification data to the second device, where the first device and second device are mobile devices; receiving an indication of proximity from the second device; and notifying the first device of the indication of proximity.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a divisional of and claims priority to U.S. patentapplication Ser. No. 13/802,290, filed on Mar. 13, 2013, which is anon-provisional of and claims priority to U.S. Provisional PatentApplication No. 61/736,439, filed on Dec. 12, 2012, the entire contentsof which are hereby incorporated by reference.

TECHNICAL FIELD

This disclosure relates to detecting proximity using WiFi hotspots.

BACKGROUND

Mobile devices can determine proximity to each other based on location.Each device can obtain a current location. Generally, to obtain acurrent location, a mobile device can use data based on threesources: 1) WiFi hotspots, 2) cellular towers, or 3) a GlobalPositioning System (GPS). In particular, the mobile device sends datafrom any of the three sources to a server, and the server responds withlocation coordinates, e.g., longitude and latitude coordinates. A mobiledevice can compare its location to other devices' locations, e.g., bymeasuring distance between locations, to determine proximity. Forexample, if the measured distances are lower than a predeterminedthreshold, the devices can be determined to be in proximity to eachother.

SUMMARY

This specification relates to determining proximity between mobiledevices using WiFi hotspots. A first device identifies hotspotssurrounding the first device. In some implementations, the first devicehashes the identified hotspots into a hash value. The first device sendsthe hash value to a server system. The server system can send the hashvalue to a second device. The second device can compare the receivedhash value to a hashed value of WiFi hotspots that surround the seconddevice. If the hash values are equivalent, the second device determinesit is in proximity to the first device.

In one aspect, a method includes receiving hotspot identification datafrom the first device, where the identification data identifies aplurality of WiFi hotspots that are in proximity to the first device;determining that the second device is associated with the first device;sending the hotspot identification data to the second device, where thefirst device and second device are mobile devices; receiving anindication of proximity from the second device; and notifying the firstdevice of the indication of proximity.

Implementations may include one or more of the following features. Thehotspot identification data is a hash value of the MAC addresses and/ornames of the plurality of WiFi hotspots. The hotspot identification datais a list of the MAC addresses and/or names of the plurality of WiFihotspots. The notifying includes sending, to the first device, theindication of proximity of the second device and data associated withthe second device. The data associated with the second device includespersonal identifying information of a user of the second device.Receiving, from the first device, data indicating a payment transactionbetween the first device and the second device; and submitting thetransaction to a financial service for authorization. The determiningcomprises determining the second device has given an indication ofconsent to interact with the first device. The first device is acustomer device, and a second device is a merchant device, furthercomprising: prior to sending the hotspot identification data to thesecond device, determining the customer device has given an indicationof consent to perform a cardless payment transaction with the merchantdevice.

In another aspect, a method of determining proximity between a firstdevice and a second device, comprising: receiving first hotspotidentification data from a server system, the first hotspotidentification data identifying a first plurality of WiFi hotspots inproximity to the first device; identifying second hotspot identificationdata that indicates a second plurality of WiFi hotspots in proximity tothe second device, where the first device and the second device aremobile devices; determining whether the first device and the seconddevice are in proximity to each other based at least on a comparisonbetween the first hotspot identification data and the second hotspotidentification data; and if the first device and the second device arein proximity to each other, sending an indication of proximity to theserver system.

Implementations may include one or more of the following. The first andsecond hotspot identification data are hash values of the firstplurality of WiFi hotspots and second plurality of WiFi hotspots,respectively. The first and second hotspot identification data are listsof the MAC (media access control) addresses and/or names of the firstplurality of WiFi hotspots and second plurality of WiFi hotspots,respectively. The identifying occurs periodically after an interval oftime. The determining occurs when the second device detects one or morechanges in the second plurality of WiFi hotspots. The first device andthe second device are in proximity to each other if the hash values ofthe first plurality of WiFi hotspots and the second plurality of WiFihotspots are equivalent. The first device is a merchant device, thesecond device is a customer device, and the server system is a cardlesspayment system.

Advantages may include one or more of the following. Proximity can bedetermined without determining locations, e.g., latitude and longitude,of a first mobile device and a second mobile device. When a systemdetermines whether two devices are in proximity to each other, theidentities of surrounding WiFi hotspots around the two devices remainprivate through use of hash values. Proximity determination can occur ona local mobile device instead of on an external system, reducing needfor wireless communication and thereby saving battery on the localdevice.

In some implementations, the first device is a merchant device and thesecond device is a customer device. A merchant device can be providedwith a list of nearby customer devices that have given an indication ofconsent to perform a transaction. By limiting transactions to customerdevices that are in proximity to the merchant device, the merchantdevice can prevent unauthorized transactions with customer devices thatare not in proximity to the merchant device. This enhances security forboth the merchant and the customer. Also, if the merchant device isnotified when the customer device is in proximity, the merchant canprovide a personalized experience to the customer.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic illustration of an example proximity detectionsystem architecture.

FIG. 2 is a diagram of an example flow chart of a server systemprocessing WiFi hotspots to determine proximity between a first deviceand a second device.

FIG. 3 is a diagram of an example flow chart of the customer devicedetermining whether it is in proximity to the merchant device.

FIGS. 4A-B are diagrams of example maps of mobile devices that are andare not in proximity to each other.

Like reference numbers and designations in the various drawings indicatelike elements.

DETAILED DESCRIPTION

FIG. 1 is a schematic illustration of an example proximity detectionsystem architecture 100. A first mobile device 102 detects whether asecond mobile device 116 is in proximity using a server system 110.Mobile devices 102, 116 communicate with the server system 110 over theInternet 108. The mobile devices 102, 116 can connect to the Internet108 using a cellular data connection, e.g., 3G or 4G, or a wirelesslocal area network connection, e.g., WiFi. Each mobile device 102, 116includes a WiFi detector 104, 112 and a hash controller 106, 114.

The WiFi detectors 104, 112 identify WiFi hotspots (or “wireless accesspoints (WAPs)”) surrounding the respective mobile device. Whenidentifying WiFi hotspots, the respective mobile device can receive fromthe hotspot a MAC address to connect to and a name of the WiFi hotspot.WiFi hotspots generally have a limited range. As a mobile device changeslocations, a WiFi detector in the mobile device can identify new WiFihotspots that are within range of the mobile device. In other words, themobile device can detect when surrounding WiFi hotspots change.

The hash controllers 106, 114 generate and compare hash values. Hashvalues are generated through hash functions. A hash function maps data,e.g., lists of WiFi hotspots, to hash values. In some implementations,the hash values are represented as integers. In some otherimplementations, the hash values are represented as alphanumericstrings. For example, the hash function can receive a list of MACaddresses and/or names of WiFi hotspots and can generate a hash valuefrom the list. The hash controllers 106, 114 also compare hash values.For example, mobile device 116 can receive a hash value from the serversystem 110. The mobile device 116 can determine whether the receivedhash value is equal to a generated hash value. In some implementations,generating and/or comparing hash values occur on the server system 110.

In some implementations, devices have different hash functions. Forexample, mobile device 102 can send a list of WiFi hotspots, i.e., alist of the MAC addresses and/or names of the hotspots detected by thefirst mobile device 102, to the server system 110. The server system 110can identify an appropriate hash function from a list of hash functionsfor mobile device 116, e.g., based on a unique device identification ofmobile device 116. The server system 110 can hash the list of WiFihotspots from mobile device 102 using the appropriate hash function andsend the hashed list to mobile device 116. Mobile device 116 can hash,e.g., using the same hash function used by the server system 110,surrounding WiFi hotspots and compare the hash to the received list todetermine proximity, which will be described further below in referenceto FIGS. 3 and 4.

FIG. 2 is a diagram of an example flow chart 200 of a server systemprocessing WiFi hotspots to determine proximity between a first deviceand a second device. For simplicity, the first device is described as amerchant device, and the second device is described as a customerdevice. Other types of devices are possible, e.g., the first and seconddevices can both be personal user devices.

A merchant device identifies surrounding WiFi hotspots, e.g., using aWiFi detector. The merchant device creates a list of WiFi hotspots,e.g., where each item in the list is a name of a distinct WiFi hotspot.The merchant device can send the list of WiFi hotspots to a serversystem, e.g., the server system in reference to FIG. 1. In someimplementations, the merchant device uses a hash function on the list ofWiFi hotspots to create a hash value. The hash value, e.g., analphanumeric string, represents the list of WiFi hotspots in ananonymous way. That is, generally, the list of WiFi hotspots cannot bereverse engineered from the hash value. The merchant device can send thehash value to the server system. The server system receives the list ofWiFi hotspots from the merchant device (step 202).

The server system determines whether a customer device is associatedwith the merchant device (step 204). In some implementations, the twodevices are associated if the customer device gives an indication ofconsent to interact with the merchant device. In some otherimplementations, the two devices are associated if the customer devicehas given an indication of consent to conduct a payment transaction withthe merchant device. In particular, the consent allows the server systemto notify the merchant device when the customer device is in proximityto the merchant device. The server system having an indication ofproximity between the merchant device and the customer device can be aprerequisite to conducting a payment transaction. In alternativeimplementations, the indication of proximity is only one of a fewprerequisites to conducting the payment transaction. For example, inaddition to requiring an indication of proximity, the server system canensure the customer device is within a predetermined distance from themerchant device, e.g., using geofencing technology, before conductingthe payment transaction. In some implementations, the first and seconddevices are both personal user devices and the first user has simplyauthorized the second user to detect when the first user is present,e.g., to provide this information to a social networking application onthe second user's mobile device.

In some implementations, the customer can conduct a cardless paymenttransaction with the merchant. The cardless payment transaction isdescribed in US Patent Application (Ser. No. 61/563,022), filed on Nov.22, 2011, entitled “Cardless Payment Transactions,” which isincorporated by reference herein in its entirety. The customer devicecan give, to the server system, an indication of consent to conduct acardless payment transaction with the merchant. The server system, e.g.,acting as a cardless payment system, can determine the customer deviceis associated with the merchant device when the server system receivesthe indication of consent.

When the server system determines the customer device is associated withthe merchant device, the server system sends the list of WiFi hotspotsto the customer device (step 206). In some implementations, the serversystem sends the hash value of the list of WiFi hotspots to the customerdevice.

FIG. 3 is a diagram of an example flow chart 300 of the customer devicedetermining whether it is in proximity to the merchant device. Thecustomer device receives first hotspot identification data (or“identification data”) identifying a first list of WiFi hotspots (or“wireless access points (WAPs)”) from the server system (step 302). Thehotspot identification data identifies represents WiFi hotspots thatsurround the merchant device, e.g., are able to be detected by a WiFidetector in the merchant device. In some implementations, the hotspotidentification data is received simply as the first list of WiFihotspots, i.e., the names and/or MAC addresses. In some implementations,the hotspot identification data is received as a hash value of the firstlist of WiFi hotspots. The customer device can store the received hashvalue. This allows the customer device to determine proximity withoutengaging in another network call with the server system.

The customer device identifies second hotspot identification data thatindicates a second list of WiFi hotspots that surround the customerdevice (step 304), e.g., using a WiFi detector. In some implementations,the customer device hashes the second list of WiFi hotspots into a hashvalue. The customer device can identify the second list of WiFi hotspotsin periodic intervals, e.g., every 2 to 10 minutes.

The customer device can keep track of one or more previous hash valuesand/or one or more previous lists of WiFi hotspots. If the customerdevice has not yet determined it is in proximity to the merchant device,the customer device can compare the second list of WiFi hotspots to apreviously identified list of WiFi hotspots. The lists can berepresented as hash values or as unmodified lists. If the lists of WiFihotspots are identical, e.g., the surrounding WiFi hotspots around thecustomer device have not changed, the customer device can presume it hasnot significantly moved from its previous position. Therefore, thecustomer device would not have come in proximity to the merchant device.The customer device then can wait to identify WiFi hotspots at a nextinterval, thereby saving battery.

If the second list of WiFi hotspots has changed, the customer devicedetermines whether the customer device is in proximity to the merchantdevice (step 306). The customer device compares the second list of WiFihotspots to the received first list of WiFi hotspots. If the lists ofWiFi hotspots are substantially equivalent, e.g., as unmodified lists oras hash values, the customer device determines it is in proximity to themerchant device. An example is further described below in reference toFIGS. 4A-4B. In some implementations, the customer device determines itis in proximity to the merchant device if a partial set of hotspotswithin the list of WiFi hotspots match.

In some implementations, the comparison between the first and secondlists of WiFi hotspots occurs on the server system. Therefore, insteadof receiving the first list of WiFi hotspots, the customer device sendsthe second list of WiFi hotspots, e.g., through a network call, to theserver system, e.g., as a hash value. In some implementations, thesecond list of WiFi hotspots is sent to the server system only if thelist is different from a previously identified list of WiFi hotspots.The server system can perform the comparison to determine whether thecustomer device is in proximity to the customer device. However,comparison on the server system requires more network calls from thecustomer device and thereby causes the customer device to use morebattery.

If the customer device determines it is in proximity to the merchantdevice, the customer device can send an indication of proximity to theserver system (step 308). The server system can receive the indicationand notify the merchant device of the customer device's proximity. Insome implementations, the server system determines the customer deviceis in proximity to the merchant device and the server system sends theindication of proximity to any one of the devices, as appropriate. Theserver system can send, to the merchant device, data associated with thecustomer device. The data can be personal identifying information of thecustomer, e.g., a name or picture. In some implementations, the serversystem sends the data after 1) determining proximity and 2) receivingindication of consent from the customer device to enter into a cardlesstransaction. The merchant device can process the personal identifyinginformation, e.g., by displaying the customer information on atouchscreen of the merchant device. If the merchant conducts atransaction with the customer, the merchant device can send transactioninformation, e.g., payment amount and/or merchant information, to theserver system. The server system can submit the transaction to afinancial service for authorization.

FIG. 4A is a diagram of an example map 400 of a merchant device 408 anda customer device 410 that are not in proximity to each other. Merchantdevice 408 identifies a list of surrounding WiFi hotspots: WiFi HotspotA 402 and WiFi hotspot B 404. Merchant device 408 can create a hashvalue of the list of surrounding WiFi hotspots, e.g., “A1B1.” Themerchant device 408 can send the hash value to a server system.

Customer device 410 receives the list of WiFi hotspots surroundingmerchant device 408 in hash value form. For example, customer device 410receives “A1B1” from the server system. The customer device 410 canstore the received hash value for future comparisons. The customerdevice 410 identifies a list of surrounding WiFi hotspots: WiFi hotspotC 406. The customer device generates a hash from this list, e.g., “C1.”The customer device can compare the two hashes and determine that “A1B1”is not equivalent to “C1.” Therefore, the customer device can wait for anext interval at which it will repeat this process.

FIG. 4B is a diagram of an example map of the merchant device and thecustomer device that are in proximity to each other. Following from theexample described in reference to FIG. 4A, the customer device 410 hasmoved closer to the merchant device 408. After an interval of time,customer device 410 identifies a list of surrounding WiFi hotspots: WiFiHotspot A 402 and WiFi hotspot B 402, 404. The customer device generatesa hash from this list: “A1B1.” The previous hash value of surroundingWiFi hotspots is “C1.” Because these hash values are different, thecustomer device 410 proceeds to determine whether it is in proximity tothe merchant device 408, e.g., by retrieving the received hash value. Inparticular, the customer device 410 compares this hash value, e.g.,“A1B1”, to the received hash value, e.g., “A1B1.” The customer device410 determines these hash values are equivalent and can send anindication of proximity to the server system.

In some implementations, instead of determining equivalence of hashvalues, the customer device 410 sends the indication of proximity ifsurrounding WiFi hotspots overlap. That is, the indication of proximitycan be sent if the list of surrounding WiFi hotspots around the customerdevice 410 includes one or more WiFi hotspots in common with the list ofsurrounding WiFi hotspots around the merchant device 408.

Although the discussion above has focused on the first device as amerchant device and the second device as a customer device, thetechnique described above can be used to detect the proximity of mobiledevices of other types of users, and for other applications. Forexample, both the first and second devices can both be personal userdevices, and the proximity determination can be provided to a socialnetworking application on the second user's mobile device.

Embodiments of the subject matter and the operations described in thisspecification can be implemented in digital electronic circuitry, or incomputer software, firmware, or hardware, including the structuresdisclosed in this specification and their structural equivalents, or incombinations of one or more of them. Embodiments of the subject matterdescribed in this specification can be implemented as one or morecomputer programs, i.e., one or more modules of computer programinstructions, encoded on a non-transitory computer storage medium forexecution by, or to control the operation of, data processing apparatus.Alternatively or in addition, the program instructions can be encoded onan artificially-generated propagated signal, e.g., a machine-generatedelectrical, optical, or electromagnetic signal, that is generated toencode information for transmission to suitable receiver apparatus forexecution by a data processing apparatus. A computer storage medium canbe, or be included in, a computer-readable storage device, acomputer-readable storage substrate, a random or serial access memoryarray or device, or a combination of one or more of them. Moreover,while a computer storage medium is not a propagated signal, a computerstorage medium can be a source or destination of computer programinstructions encoded in an artificially-generated propagated signal. Thecomputer storage medium can also be, or be included in, one or moreseparate physical components or media (e.g., multiple CDs, disks, orother storage devices).

The operations described in this specification can be implemented asoperations performed by a data processing apparatus on data stored onone or more computer-readable storage devices or received from othersources.

The term “data processing apparatus” encompasses all kinds of apparatus,devices, and machines for processing data, including by way of example aprogrammable processor, a computer, a system on a chip, or multipleones, or combinations, of the foregoing The apparatus can includespecial purpose logic circuitry, e.g., an FPGA (field programmable gatearray) or an ASIC (application-specific integrated circuit). Theapparatus can also include, in addition to hardware, code that createsan execution environment for the computer program in question, e.g.,code that constitutes processor firmware, a protocol stack, a databasemanagement system, an operating system, a cross-platform runtimeenvironment, a virtual machine, or a combination of one or more of them.The apparatus and execution environment can realize various differentcomputing model infrastructures, such as web services, distributedcomputing and grid computing infrastructures.

A computer program (also known as a program, software, softwareapplication, script, or code) can be written in any form of programminglanguage, including compiled or interpreted languages, declarative orprocedural languages, and it can be deployed in any form, including as astand-alone program or as a module, component, subroutine, object, orother unit suitable for use in a computing environment. A computerprogram may, but need not, correspond to a file in a file system. Aprogram can be stored in a portion of a file that holds other programsor data (e.g., one or more scripts stored in a markup languageresource), in a single file dedicated to the program in question, or inmultiple coordinated files (e.g., files that store one or more modules,sub-programs, or portions of code). A computer program can be deployedto be executed on one computer or on multiple computers that are locatedat one site or distributed across multiple sites and interconnected by acommunication network.

The processes and logic flows described in this specification can beperformed by one or more programmable processors executing one or morecomputer programs to perform actions by operating on input data andgenerating output. The processes and logic flows can also be performedby, and apparatus can also be implemented as, special purpose logiccircuitry, e.g., an FPGA (field programmable gate array) or an ASIC(application-specific integrated circuit).

Processors suitable for the execution of a computer program include, byway of example, both general and special purpose microprocessors, andany one or more processors of any kind of digital computer. Generally, aprocessor will receive instructions and data from a read-only memory ora random access memory or both. The essential elements of a computer area processor for performing actions in accordance with instructions andone or more memory devices for storing instructions and data. Generally,a computer will also include, or be operatively coupled to receive datafrom or transfer data to, or both, one or more mass storage devices forstoring data, e.g., magnetic, magneto-optical disks, or optical disks.However, a computer need not have such devices. Moreover, a computer canbe embedded in another device, e.g., a mobile telephone, a personaldigital assistant (PDA), a mobile audio or video player, a game console,a Global Positioning System (GPS) receiver, or a portable storage device(e.g., a universal serial bus (USB) flash drive), to name just a few.Devices suitable for storing computer program instructions and datainclude all forms of non-volatile memory, media and memory devices,including by way of example semiconductor memory devices, e.g., EPROM,EEPROM, and flash memory devices; magnetic disks, e.g., internal harddisks or removable disks; magneto-optical disks; and CD-ROM and DVD-ROMdisks. The processor and the memory can be supplemented by, orincorporated in, special purpose logic circuitry.

To provide for interaction with a user, embodiments of the subjectmatter described in this specification can be implemented on a computerhaving a display device, e.g., a CRT (cathode ray tube) or LCD (liquidcrystal display) monitor, for displaying information to the user and akeyboard and a pointing device, e.g., a mouse or a trackball, by whichthe user can provide input to the computer. Other kinds of devices canbe used to provide for interaction with a user as well; for example,feedback provided to the user can be any form of sensory feedback, e.g.,visual feedback, auditory feedback, or tactile feedback; and input fromthe user can be received in any form, including acoustic, speech, ortactile input. In addition, a computer can interact with a user bysending resources to and receiving resources from a device that is usedby the user; for example, by sending web pages to a web browser on auser's client device in response to requests received from the webbrowser.

Embodiments of the subject matter described in this specification can beimplemented in a computing system that includes a back-end component,e.g., as a data server, or that includes a middleware component, e.g.,an application server, or that includes a front-end component, e.g., aclient computer having a graphical user interface or a Web browserthrough which a user can interact with an implementation of the subjectmatter described in this specification, or any combination of one ormore such back-end, middleware, or front-end components. The componentsof the system can be interconnected by any form or medium of digitaldata communication, e.g., a communication network. Examples ofcommunication networks include a local area network (“LAN”) and a widearea network (“WAN”), an inter-network (e.g., the Internet), andpeer-to-peer networks (e.g., ad hoc peer-to-peer networks).

The computing system can include clients and servers. A client andserver are generally remote from each other and typically interactthrough a communication network. The relationship of client and serverarises by virtue of computer programs running on the respectivecomputers and having a client-server relationship to each other. In someembodiments, a server transmits data (e.g., an HTML page) to a clientdevice (e.g., for purposes of displaying data to and receiving userinput from a user interacting with the client device). Data generated atthe client device (e.g., a result of the user interaction) can bereceived from the client device at the server.

A system of one or more computers can be configured to performparticular operations or actions by virtue of having software, firmware,hardware, or a combination of them installed on the system that inoperation causes or cause the system to perform the actions. One or morecomputer programs can be configured to perform particular operations oractions by virtue of including instructions that, when executed by dataprocessing apparatus, cause the apparatus to perform the actions.

While this specification contains many specific implementation details,these should not be construed as limitations on the scope of anyinventions or of what may be claimed, but rather as descriptions offeatures specific to particular embodiments of particular inventions.Certain features that are described in this specification in the contextof separate embodiments can also be implemented in combination in asingle embodiment. Conversely, various features that are described inthe context of a single embodiment can also be implemented in multipleembodiments separately or in any suitable subcombination. Moreover,although features may be described above as acting in certaincombinations and even initially claimed as such, one or more featuresfrom a claimed combination can in some cases be excised from thecombination, and the claimed combination may be directed to asubcombination or variation of a subcombination.

Similarly, while operations are depicted in the drawings in a particularorder, this should not be understood as requiring that such operationsbe performed in the particular order shown or in sequential order, orthat all illustrated operations be performed, to achieve desirableresults. In certain circumstances, multitasking and parallel processingmay be advantageous. Moreover, the separation of various systemcomponents in the embodiments described above should not be understoodas requiring such separation in all embodiments, and it should beunderstood that the described program components and systems cangenerally be integrated together in a single software product orpackaged into multiple software products.

Thus, particular embodiments of the subject matter have been described.Other embodiments are within the scope of the following claims. In somecases, the actions recited in the claims can be performed in a differentorder and still achieve desirable results. In addition, the processesdepicted in the accompanying figures do not necessarily require theparticular order shown, or sequential order, to achieve desirableresults. In certain implementations, multitasking and parallelprocessing may be advantageous.

What is claimed is:
 1. A method of determining, at a server system,proximity between a first device and a second device, the server systemincluding memory for storing instructions and at least one processor forexecuting the instructions to perform the method of determining, themethod of determining comprising: receiving identification data from thefirst device, where the identification data identifies a plurality ofwireless access points that are in proximity to the first device;determining that the second device is associated with the first device;sending at least a portion of the identification data to the seconddevice, where the first device and second device are mobile devices;receiving an indication of proximity from the second device; andnotifying the first device of the indication of proximity.
 2. The methodof claim 1, where the at least the portion of the identification datacomprises a hash value of at least one of MAC addresses or names of theplurality of wireless access points.
 3. The method of claim 1, where theat least the portion of the identification data comprises a list of atleast one of MAC addresses or names of the plurality of wireless accesspoints.
 4. The method of claim 1, where the notifying includes sending,to the first device, the indication of proximity of the second deviceand data associated with the second device.
 5. The method of claim 4,where the data associated with the second device includes personalidentifying information of a user of the second device.
 6. The method ofclaim 1, further comprising: receiving, from the first device, dataindicating a payment transaction between the first device and the seconddevice; and submitting the payment transaction to a financial servicefor authorization.
 7. The method of claim 1, where the determiningcomprises determining that the second device has given an indication ofconsent to interact with the first device.
 8. The method of claim 1,where the first device is a customer device, and the second device is amerchant device, further comprising: prior to sending the at least aportion of the identification data to the second device, determiningthat the customer device has given an indication of consent to perform acardless payment transaction with the merchant device.
 9. A computerprogram product encoded on a non-transitory computer storage mediumoperable on a computing device including at least one data processingapparatus that executes the stored computer program product to cause theat least one data processing apparatus to perform operations comprising:receiving identification data from a first device, where theidentification data identifies a plurality of wireless access pointsthat are in proximity to the first device; determining that a seconddevice is associated with the first device; sending at least a portionof the identification data to the second device, where the first deviceand second device are mobile devices; receiving an indication ofproximity from the second device; and notifying the first device of theindication of proximity.
 10. The computer program product of claim 9,where the at least the portion of the identification data comprises ahash value of at least one of MAC addresses or names of the plurality ofwireless access points.
 11. The computer program product of claim 9,where the at least the portion of the identification data comprises alist of the at least one of MAC addresses or names of the plurality ofwireless access points.
 12. The computer program product of claim 9,where the notifying includes sending, to the first device, theindication of proximity of the second device and data associated withthe second device.
 13. The computer program product of claim 12, wherethe data associated with the second device includes personal identifyinginformation of a user of the second device.
 14. The computer programproduct of claim 9, further comprising: receiving, from the firstdevice, data indicating a payment transaction between the first deviceand the second device; and submitting the payment transaction to afinancial service for authorization.
 15. The computer program product ofclaim 9, where the determining comprises determining that the seconddevice has given an indication of consent to interact with the firstdevice.
 16. The computer program product of claim 9, where the firstdevice is a customer device, and the second device is a merchant device,further comprising: prior to sending the at least the portion of theidentification data to the second device, determining that the customerdevice has given an indication of consent to perform a cardless paymenttransaction with the merchant device.
 17. A system comprising one ormore computers, each of the one or more computers including a memory forstoring instructions and at least one processor for executing theinstructions to perform operations comprising: receiving identificationdata from a first device, where the identification data identifies aplurality of wireless access points that are in proximity to the firstdevice; determining that a second device is associated with the firstdevice; sending at least a portion of the identification data to thesecond device, where the first device and second device are mobiledevices; receiving an indication of proximity from the second device;and notifying the first device of the indication of proximity.
 18. Thesystem of claim 17, where the at least the portion of the identificationdata comprises a hash value of at least one of MAC addresses or names ofthe plurality of wireless access points.
 19. The system of claim 17,where the at least the portion of the identification data comprises alist of at least one of MAC addresses or names of the plurality ofwireless access points.
 20. The system of claim 17, where the notifyingincludes sending, to the first device, the indication of proximity ofthe second device and data associated with the second device.
 21. Thesystem of claim 20, where the data associated with the second deviceincludes personal identifying information of a user of the seconddevice.
 22. The system of claim 17, further comprising: receiving, fromthe first device, data indicating a payment transaction between thefirst device and the second device; and submitting the paymenttransaction to a financial service for authorization.
 23. The system ofclaim 17, where the determining comprises determining that the seconddevice has given an indication of consent to interact with the firstdevice.
 24. The system of claim 17, where the first device is a customerdevice, and the second device is a merchant device, further comprising:prior to sending the at least the portion of the identification data tothe second device, determining that the customer device has given anindication of consent to perform a cardless payment transaction with themerchant device.